Fluorophotometric Determination of Trace Amounts of Chromium(Ⅵ) in Water Samples Based on the Fluorescence Quenching of Safranine T

Quenching of fluorescence of safranine T by oxidation reaction with Cr(Ⅵ) in an acidic medium of 0.12 mol·L-1 HCl was observed.Linear relationship between values of decrease in fluorescence intensity (ΔF=F0-F) and concentration of Cr(Ⅵ) was obtained in the range within 128 μg·L-1,when measured at wavelengths of 559.0 nm (λex) and 575.0 nm (λem).Detection limit (3S/N) found was 2.5 μg·L-1.Based on these facts,a fluorophotometric method for determination of traces of Cr(Ⅵ) in water samples (i.e.electroplating waste water,industrial waste water,tap water and lake water) was proposed.In its application to the analysis of several water samples,the results obtained were in consistency with the results obtained by the diphenylcarbazide-photometric method.Values of recovery found by standard addition method were ranged from 98.2% to 105.0%,and values of RSD′s (n=6) were in the range of 1.7% to 2.7%.